There are two competing reactions for hypochlorite:
2ClO->2Cl-+O2
3ClO->2Cl-+ClO3-
Both are effectively irreversible. Both should be promoted by higher temperature but also higher concentration of hypochlorite. So which conditions
favour which?
Hypochlorite solutions can exist at temperatures below freezing, too. Not its own, but solutes lower water freezing point. Instead of evaporation, you
could concentrate bleach by freezing and skimming off pure ice as it floats to top... which still would increase the concentration and thereby promote
decay.
At low temperatures, sodium hypochlorite precipitates from saturated solutions as NaClO*5H2O. |